Predominantly firearms with multiple firing modes are used only in military applications and firearms that are currently available that have more than one firing mode are strictly mechanical in nature. Mechanical systems have been relied upon by the military because they are very reliable and because in a military setting a malfunctioning weapon can mean the difference between life and death. Present mechanical systems have been well-refined and rarely fail.
However, when introducing additional firing modes, the resulting mechanics do become more complex. System complexities are compounding—a fully automatic weapon is more complex and has more moving parts than a semi-automatic weapon which in turn has more moving parts than a non-autoloading weapon. A fully automatic weapon that has multiple modes of firing is yet more mechanically complex a standard fully automatic weapon. And thus, in addition to the compounding of mechanical complexity of assembly, maintenance and repair, there exists greater number of parts that can wear and will eventually fail.
Any assault or military style weapon must at the very least have a semi-automatic mode of fire. However, most weapons, in addition to semi-automatic mode of fire, have a fully automatic mode of fire and a burst mode of fire. These modes allow a soldier to have some choices on the battle field. Despite the availability of multiple modes of fire in a mechanical package, the modes themselves have limits. Full automatic mode can be problematic because soldiers have the ability to completely empty their weapon of ammunition in a moment of panic. Also limiting, is that once a gun has been timed, it is impossible to adjust the automatic rate of fire.
Also of note, due to the complexities of burst mechanisms, there is not a firearm in existence with more than two burst modes.
A helpful improvement to automatic weapons was the burst mode of fire. In this mode, a single squeeze of the trigger will cause the gun to fire a predetermined number of rounds, usually three, at a time. This has the added benefit of providing a limited automatic firing mode but prevents the soldier from emptying his weapon of ammunition in a moment of panic or poor decision-making which can easily occur in the heat of battle. The limitation, however, with mechanical burst mode is that that not only can the rate of fire still not be controlled, but the burst mechanism is complex and, as soldiers have reported, is prone to rapid wear. Moreover, the number of rounds fired in mechanical weapon having burst mode cannot easily be manipulated in the field to fit the exigencies of the situation or to mislead the enemy.
Despite these shortcomings of mechanical systems, the unreliability of an electronic system has prevented militaries from arming their soldiers with non-mechanical systems. This is primarily due to reluctance to rely on weapons that require batteries or that do not perform properly when wet or even submersed in water.
In non-military settings, electronic systems for firing weapons have been previously developed, and these systems have typically entirely replaced the mechanical components of the weapon except the trigger itself. For example, electronic systems have replaced mechanical triggers in some competition target shooting weapons because it is widely believed that the physical movement of such mechanical systems can affect the shooters aim. Also, these firearms typically not engineered to be capable of multi-modes of firing for the reasons that competition target shooting typically does not require more than a single shot mode of firing, many shooting ranges discourage rapid-fire shooting for reasons of safety, and that in the United States and many other countries it is illegal for most private citizens to possess automatically repeating firearms with a special license or permit.
Paintball guns, which are not true firearms, have also utilized electronic triggers in place of mechanical triggers. Paintball guns are not true firearms because the common definition of “firearm” requires the weapon to ignite gunpowder to fire a projectile and paintball guns use compressed air. As a result, a paintball gun does not use any of the same mechanical parts, such as a hammer or sear, to fire a projectile, and instead uses a trigger actuated valve that allows a controlled release of compressed air from an air storage reservoir to launch a projectile. Regardless, some paintball guns have replaced mechanical actuated valving with electrically actuated valving because rapid fire is beneficial to paintball games and possessing an automatically firing paintball gun is not illegal in the United States or most (if not all) countries. However, reliability in the paintball art is not such great concern as in military and failures are more acceptable. Though it is doubtful that electric paintball mechanisms used to launch a ball of paint with air could be adapted to a firearm used to ignite gunpowder to fire a bullet, such systems would still be insufficient.
Finally, weapons that attempt to mechanically operate a trigger, such as mounted to a gun to actuate a trigger, have been invented. Such devices do not work well and are unreliable. Such devices more resemble silly gimmicks and have been soundly rejected in nearly all, including military, applications. Moreover, these devices, when mounted to a gun, typically prevent the usage of a trigger by a user's finger and require some other means of actuation that make the gun more dangerous to operate and accurately fire.
One attempt at an electronically-controlled firearm is disclosed in U.S. Pat. No. 5,713,150 to Ealovega. Ealovega uses a piezo-electrically actuated sear to control, after an initial trigger pull, the hammer action of the gun. As the shooter holds down the trigger, an electronic switch (96) sends a signal to the piezoelectric member (62) to trip the piezo-electrically actuated sear and thus fire the weapon. Therefore, Ealovega uses a piezoelectric device in place of a known mechanical device to create an automatic firing mode. As a result, the weapon of Ealovega cannot be fired initially in an electronic mode but must be manually fired with an initial mechanical trigger pull. Therefore, the first pull of Ealovega requires a manual trigger pull which negatively affects shooter aim.
Another problem with Ealovega, is the addition of additional moving parts instead of the elimination of moving parts. Moreover, the electronic components of Ealovega, and particularly the piezoelectric device, are housed within the lower receiver of the weapon. The lower receiver very rapidly fills up with carbon due to gases which operate the action of the weapon being redirected from the barrel to the lower receiver. Carbon soot is a conductive and corrosive material which tends to short out and corrode electronic components. Moreover, lubricating oil present in the lower receiver to lubricate the many moving parts further exposes electronic components to destructive contaminants.
Therefore, a need exists for an electronic automatic firing weapon with multiple firing modes, and preferably a burst mode, that can control the rate of rounds fired in both burst and automatic mode, number of rounds fired in burst, or to provide additional modes of firing that have the ability to deceive the enemy.